Quad-lock or similar phone mount?

I tried the search function, but you know....

Anyway, is anyone using the quad-lock phone mounting system or something similar (SP Connect, Topeak, etc) that can give some insight into whether they work well? As to the Quad-lock in particular, what is the shortest stem it can fit on?

Had one that worked fine. Stayed on great. Don't really use my phone that way anymore, but still using the case as a case sometimes. I think I had it on 70 our 80mm stem, but might have just had it on the bar.

OK, I dug around in the Drawer of Random Shit I'd Forgotten About (tm) and found my mount. At lease with the version I have, I think 70mm could be awkward, depending on design, and you're not going shorter than that. But it snugs up pretty tight to the stem when mounted on the bar and seems stable enough like that.

I bought the Gear Lock case for my Samsung S10E and Out Front mount last summer. I rode a ton of bike park and CO XC with it. I didn't use the mount for races but definitely rode fast and even had a crash or two. The phone stayed on great.

I kept the case on for winter and it was slim enough to not be noticed and kept the phone free from damage.